Saline soluble inorganic fibres

ABSTRACT

Thermal insulation is provided for use in applications requiring continuous resistance to temperatures of 1260° C. without reaction with alumino-silicate firebricks, the insulation comprises fibres having a composition in wt % 
       65%&lt;SiO 2 &lt;86% 
       MgO&lt;10% 
       14%&lt;CaO&lt;28% 
       Al 2 O 3 &lt;2% 
       ZrO 2 &lt;3% 
       B 2 O 3 &lt;5% 
       P 2 O 5 &lt;5% 
       72%&lt;SiO 2 +ZrO 2 +B 2 O 3 +5*P 2 O 5    
       95%&lt;SiO 2 +CaO+MgO+Al 2 O 3 +ZrO 2 +B 2 O 3 +P 2 O 5    
     Addition of elements selected from the group Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, Y or mixtures thereof improves fibre quality and the strength of blankets made from the fibres.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application based on andclaiming priority on U.S. patent application Ser. No. 10/493,340 filedon Apr. 22, 2004, which is the U.S. national phase of InternationalApplication No. PCT/GB03/0003 filed on Jan. 2, 2003 and published inEnglish as International Publication No. WO 2003/059835 A1 on Jul. 24,2003, which application claims priority to Great Britain Application No.0200162.6 filed on Jan. 4, 2002, now British Patent 238793, the contentsof which are incorporated by reference therein.

INTRODUCTION AND BACKGROUND

This invention relates to saline soluble, non-metallic, amorphous,inorganic oxide, refractory fibrous materials. The inventionparticularly relates to glassy fibres having silica as their principalconstituent.

Inorganic fibrous materials are well known and widely used for manypurposes (e.g. as thermal or acoustic insulation in bulk, mat, orblanket form, as vacuum formed shapes, as vacuum formed boards andpapers, and as ropes, yarns or textiles; as a reinforcing fibre forbuilding materials; as a constituent of brake blocks for vehicles). Inmost of these applications the properties for which inorganic fibrousmaterials are used require resistance to heat, and often resistance toaggressive chemical environments.

Inorganic fibrous materials can be either glassy or crystalline.Asbestos is an inorganic fibrous material one form of which has beenstrongly implicated in respiratory disease.

It is still not clear what the causative mechanism is that relates someasbestos with disease but some researchers believe that the mechanism ismechanical and size related. Asbestos of a critical size can piercecells in the body and so, through long and repeated cell injury, have abad effect on health. Whether this mechanism is true or not regulatoryagencies have indicated a desire to categorise any inorganic fibreproduct that has a respiratory fraction as hazardous, regardless ofwhether there is any evidence to support such categorisation.Unfortunately for many of the applications for which inorganic fibresare used, there are no realistic substitutes.

Accordingly there is a demand for inorganic fibres that will pose aslittle risk as possible (if any) and for which there are objectivegrounds to believe them safe.

A line of study has proposed that if inorganic fibres were made thatwere sufficiently soluble in physiological fluids that their residencetime in the human body was short; then damage would not occur or atleast be minimised. As the risk of asbestos linked disease appears todepend very much on the length of exposure this idea appears reasonable.Asbestos is extremely insoluble.

As intercellular fluid is saline in nature the importance of fibresolubility in saline solution has long been recognised. If fibres aresoluble in physiological saline solution then, provided the dissolvedcomponents are not toxic, the fibres should be safer than fibres whichare not so soluble. The shorter the time a fibre is resident in the bodythe less damage it can do. H. Förster in ‘The behaviour of mineralfibres in physiological solutions’ (Proceedings of 1982 WHO IARCConference, Copenhagen, Volume 2, pages 27-55 (1988)) discussed thebehaviour of commercially produced mineral fibres in physiologicalsaline solutions. Fibres of widely varying solubility were discussed.

International Patent Application No. WO87/05007 disclosed that fibrescomprising magnesia, silica, calcia and less than 10 wt % alumina aresoluble in saline solution. The solubilities of the fibres disclosedwere in terms of parts per million of silicon (extracted from the silicacontaining material of the fibre) present in a saline solution after 5hours of exposure. The highest value revealed in the examples had asilicon level of 67 ppm. In contrast, and adjusted to the same regime ofmeasurement, the highest level disclosed in the Förster paper wasequivalent to approximately 1 ppm. Conversely if the highest valuerevealed in the International Patent Application was converted to thesame measurement regime as the Förster paper it would have an extractionrate of 901,500 mg Si/kg fibre—i.e. some 69 times higher than any of thefibres Förster tested, and the fibres that had the highest extractionrate in the Förster test were glass fibres which had high alkalicontents and so would have a low melting point. This is convincinglybetter performance even taking into account factors such as differencesin test solutions and duration of experiment.

International Patent Application No. WO89/12032 disclosed additionalfibres soluble in saline solution and discusses some of the constituentsthat may be present in such fibres.

European Patent Application No. 0399320 disclosed glass fibres having ahigh physiological solubility.

Further patent specifications disclosing selection of fibres for theirsaline solubility include for example European 0412878 and 0459897,French 2662687 and 2662688, PCT WO86/04807, WO90/02713, WO92/09536,WO93/22251, WO94/15883, WO97/16386 and U.S. Pat. No. 5,250,488.

The refractoriness of the fibres disclosed in these various prior artdocuments varies considerably and for these alkaline earth silicatematerials the properties are critically dependent upon composition.

WO94/15883 disclosed a number of fibres that are usable as refractoryinsulation at temperatures of up to 1260° C. or more. These fibrescomprised CaO, MgO, SiO₂, and optionally ZrO₂ as principal constituents.Such fibres are frequently known as CMS (calcium magnesium silicate) orCMZS ((calcium magnesium zirconium silicate) fibres. WO94/15883 requiredthat any alumina present only be in small quantities.

A drawback found in use of these fibres, is that at temperatures betweenabout 1300° C. and 1350° C. the fibres undergo a considerable increasein shrinkage. Typically, shrinkages increase from about 1-3% at 1200°C.; to, say, 5% or more at 1300° C.; to >20% at 1350° C. This meansthat, for example, a temperature overrun on a furnace can result indamage to the insulation and hence to the furnace itself.

A further drawback is that calcium magnesium silicate fibres can reactwith, and stick to, alumina containing materials due to formation of aeutectic composition. Since aluminosilicate materials are widely usedthis is a major problem.

WO97/16386 disclosed fibres that are usable as refractory insulation attemperatures of up to 1260° C. or more. These fibres comprised MgO,SiO₂, and optionally ZrO₂ as principal constituents. As with WO94/15883,this patent required that any alumina present only be in smallquantities.

While these fibres do not show the dramatic change in shrinkage evidentin the fibres of WO94/15883, they do show a significantly highershrinkage at normal use temperatures typically having a shrinkage of3-6% over the range 1200° C.-1450° C. These fibres do not appear to havethe drawback of reacting with and sticking to alumina containingmaterials, however they tend to be difficult to make.

SUMMARY OF INVENTION

The applicants have invented a group of fibres that have a lowershrinkage across a range of temperatures than the fibres of WO97/16386,while having a higher onset of increase in shrinkage, and a more gentlechange in shrinkage, than the fibres of WO94/15883 and which also have areduced tendency to react with and stick to alumina.

Accordingly, the present invention provides thermal insulation for usein applications requiring continuous resistance to temperatures of 1260°C. without reaction with alumino-silicate firebricks, the insulationcomprising fibres having a composition in wt %

65%<SiO₂<86%

MgO<10%

14%<CaO<28%

Al₂O₃<2%

ZrO₂<3%

B₂O₃<5%

P₂O₅<5%

72%<SiO₂+ZrO₂+B₂O₃+5*P₂O₅

95%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.

A preferred range of compositions is:—

72%<SiO₂<80%

18%<CaO<26%

0%<MgO<3%

0%<Al₂O₃<1%

0%<ZrO₂<1.5%

98.5%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.

A still more preferred range has the composition:—

72%<SiO₂<74%

24%<CaO<26%

Additionally, the applicants have found that addition of small amountsof lanthanide elements, particularly lanthanum, improves the quality ofthe fibres, particularly their length and thickness, such that improvedstrength results. There is a trade-off in terms of slightly lowersolubility, but the improved strength is of help, particularly in makingsuch products as blankets, in which the fibres are needled to form aninterlocking web of fibres.

Accordingly, the present invention comprises a silicate fibrecomprising:—

65%<SiO₂<86%

MgO<10%

14%<CaO<28%

Al₂O₃<2%

ZrO₂<3%

B₂O₃<5%

P₂O₅<5%

72%<SiO₂+ZrO₂+B₂O₃+5*P₂O₅

95%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.

0.1%<R₂O₃<4%

where R is selected from the group Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Th,Dy, Ho, Er, Tm, Yb, Lu, Y or mixtures thereof.

The preferred elements are La and Y. Preferably, to achieve significantimprovements in fibre quality, the amount of R₂O₃ is greater than 0.25%,more preferably >0.5%, and still more preferably >1.0%. To minimise thereduction is solubility that occurs, the amount of R₂O₃ is preferably<2.5%, still more preferably <1.5% by weight. Very good results areobtained for a fibre having the composition in wt %:—

-   -   SiO₂:—73±0.5%    -   CaO:—24±0.5%    -   La₂O₃:—1.3−1.5%    -   Remaining components:—<2%, preferably <1.5%

BRIEF DESCRIPTION OF DRAWING

Further features of the invention will become apparent from the claimsin the light of the following illustrative description and withreference to the drawing

FIG. 1 which is a graph of shrinkage against temperature of some fibresaccording to the present invention in comparison with some commercialfibres.

DETAILED DESCRIPTION OF INVENTION

The inventors produced a range of calcium silicate fibres using anexperimental rig in which a melt was formed of appropriate composition,tapped through a 8-16 mm orifice, and blown to produce fibre in a knownmanner. (The size of the tap hole was varied to cater for the viscosityof the melt—this is an adjustment that must be determined experimentallyaccording to the apparatus and composition used).

The fibres were tested and the results for fibres that are predominantlycalcium silicate fibres with some MgO are shown in Table 1, in which:—

-   -   shrinkage figures are shown as measured on a preform of fibre by        the method (see below),    -   compositions are shown as measured by x-ray fluorescence with        boron by wet chemical analysis,    -   total solubility in ppm of the major glass components after a 24        hour static test in a physiological saline solution is shown,    -   specific surface area in m² g,    -   a qualitative assessment of fibre quality,    -   and an indication of whether the preform stuck to an        aluminosilicate brick (JM 28 bricks obtainable from Thermal        Ceramics Italiana and having an approximate composition 70 wt %        alumina and 30 wt % silica)

The shrinkage was measured by the method of manufacturing vacuum castpreforms, using 75 g of fibre in 500 cm³ of 0.2% starch solution, into a120×65 mm tool. Platinum pins (approximately 0.1-0.3 mm diameter) wereplaced 100×45 mm apart in the 4 corners. The longest lengths (L1 & L2)and the diagonals (L3 & L4) were measured to an accuracy of ±5 m using atravelling microscope. The samples were placed in a furnace and rampedto a temperature 50° C. below the test temperature at 300° C./hour andramped at 120° C./hour for the last 50° C. to test temperature and leftfor 24 hours. On removal from the furnace the samples were allowed tocool naturally. The shrinkage values are given as an average of the 4measurements.

The inventors found that those fibres having a silica content less than72% by weight tended to stick to the aluminosilicate brick. They alsofound that high MgO content fibres (>12%) did not stick (as predictedfrom the properties of WO97/16386).

It is known that calcium silicate fibres having an intermediate level ofMgO (12-20%) stick to aluminosilicate brick, whereas magnesium silicatefibres do not. Surprisingly, for the fibres of the present invention,such intermediate levels of MgO can be tolerated. Levels of <10% MgO, or<5% MgO give the non-sticking results required, but it appearspreferable for refractoriness to have a maximum level of MgO at 2.5% byweight, and more preferably the amount should be below 1.75% by weight.

Table 2 shows the effect of alumina and zirconia on these fibres.Alumina is known to be detrimental to fibre quality and the first threecompositions of Table 2 have over 2% Al₂O₃ and stick to aluminosilicatebrick. Additionally, increased alumina leads to lowered solubility.Accordingly, the inventors have determined 2% as the upper limit foralumina in their inventive compositions.

In contrast zirconia is known to improve refractoriness and Table 2shows that silica levels of below 72% can be tolerated if the amount ofZrO₂ is sufficient that the sum of SiO₂ and ZrO₂ is greater than 72% byweight. However, increasing zirconia lowers the solubility of the fibresin physiological saline solution and so the preferred level of ZrO₂ isless than 3%.

The effect of some other common glass additives is indicated by Table 3,which shows the effect of P₂O₅ and B₂O₃ as glass forming additives. Itcan be seen that P₂O₅ has a disproportionate effect on the stickingproperties of these compositions, as fibres with as low as 67.7% SiO₂ donot stick to aluminosilicate brick.

B₂O₃ also has an effect with fibres having as low as 70.9% SiO₂ notsticking. The inventors have determined that sticking to aluminosilicatebrick tends not to occur for fibres meeting the relationship:—

72%<SiO₂+B₂O₃+ZrO₂+5*P₂O₅.

The inventors have assumed a maximum level for B₂O₃ and P₂O₅ of 5% byweight each.

Tables 1 to 3 show that minor amounts of other components may beincluded and the invention tolerates up to 5% of other ingredients, butpreferably these other ingredients amount to less than 2%, morepreferably less than 1%, since such other ingredients tend to make thefibres less refractory. (But see below for effect of specific lanthanideadditives).

The above results were obtained on an experimental rig, with all of theuncertainties that entails. Production trials of the most favourableappearing fibres were conducted on two separate sites to allow bothblowing and spinning of the compositions to be tried. Table 4 shows aselection of the results obtained (duplicates omitted) and shows that avery usable fibre results. The fibres tested in the production trialshad compositions falling in the approximate range

72%<SiO₂<80%

18%<CaO<26%

0%<MgO<3%

0%<Al₂O₃<1%

0%<ZrO₂<1.5%

with

98.5%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.

It can be seen that the compositions with an MgO level of greater than1.75% tended to have a higher shrinkage at 1350° C. than those with alower MgO level.

FIG. 1 shows in graphical form an important feature of the fibres of theinvention and compares the shrinkage characteristics of the first threefibres and 5^(th) fibres of Table 4 (each referred to as SW613) withcommercial fibres Isofrax® (a magnesium silicate fibre from UnifraxCorporation), RCF (a standard aluminosilicate refractory ceramic fibre),and SW607 Max™, SW607™, and SW612™ (calcium magnesium silicate fibresfrom Thermal Ceramics Europe Limited).

It can be seen that Isofrax® and RCF have a shrinkage that is in therange 3-6% over the range 1200 to 1450° C. SW607 Max™, SW607™, andSW612™ have shrinkages in the range 2-5% at 1200° C. but increaserapidly after 1300° C. The fibres of the present invention have ashrinkage of less than 2% up to 1350° C., drift up to 5-8% at 1400° C.and accelerate thereafter.

The fibres of the present invention therefore have the advantage of alower shrinkage than magnesium silicate, commercial calcium magnesiumsilicate, or RCF fibres at 1300° C.; commence their increase inshrinkage at a higher temperature than commercial calcium magnesiumsilicate fibres; have a shallower rise in shrinkage with temperaturethan commercial calcium magnesium silicate fibres; and do not stick toaluminosilicate brick in the way commercial calcium magnesium silicatefibres may.

The fibres can be used in thermal insulation and may form either aconstituent of the insulation (e.g. with other fibres and/or fillersand/or binders) or may form the whole of the insulation. The fibres maybe formed into blanket form insulation.

A problem found with the plain calcium silicate fibres described abovewas that the fibres tend to be short resulting in a poor qualityblanket. A means of producing better fibre for blanket was required andthe applicants conducted screening tests to investigate the effect onfibre quality of the addition of other elements as additives to thecomposition. It was found that lanthanide elements, particularly La andY improved fibre quality. La was determined to be the most commerciallyinteresting element and so after this initial screening test effortscentred on investigating the effect of La.

La₂O₃ was used as an additive in amounts of 0-4% to a fibre comprising73.5% SiO₂ and balance CaO and minor impurities to determine the optimumamount. It was determined that addition of La₂O₃ improved fiberisationwhile not reducing refractoriness. The fibres did not react with aluminabricks. However, at the highest levels of La₂O₃ the solubility wasreduced significantly. Accordingly a compromise level of 1.3-1.5% La₂O₃was used for further tests on the fibre composition.

To check and define the optimum formulation in terms of refractorinessand fiberisation for the lanthanum containing material, a study wasperformed looking to the increase of silica from 67% to 78% SiO₂ in amaterial containing 1.3% La₂O₃ (kept constant), balance CaO+minorimpurities MgO and Al₂O₃.

Increasing silica increases the refractoriness of the fibre, givinglower shrinkage, higher melting point and decreases reaction withalumina at high temperature.

The best compromise between refractoriness and fiberisation was foundfor a composition of:

SiO₂ 73% CaO 24% La₂O₃ 1.3-1.5% Remaining impurities (Al₂O₃, MgO,others) <1.5%

This composition was tried on production scale manufacturing blankethaving the composition “With La” shown in Table 4 below.

It was confirmed that this composition produced better fibres than an Lafree version (“No La” in Table 4). The fibres still not reacting withalumina brick, and having good refractoriness.

Better fiberisation was observed and evaluated by looking to the tensilestrength of 25 mm thick blanket having a density 128 kg/m³.

TABLE 4 OXIDES No La With La Na₂O <0.05 0.18 MgO 0.89 0.46 Al₂O₃ 0.640.66 SiO₂ 72.9 73.2 K₂O <0.05 0.08 CaO 25.5 23.6 Fe₂O₃ 0.11 0.14 La₂O₃ 01.3 LOI 1025° C. 0.08 0.09 Total 100.1 99.7 Tensile strength 25-30 35-60128-25 blanket (kPa)

It can be seen that the addition of only 1.3% La₂O₃ results in aconsiderable improvement in tensile strength, indicating a much improvedfibre.

The applicants surmise that this effect of improving fiberisation is aviscosity or surface tension modifying effect applicable generally toalkaline earth silicate fibres, and so the invention encompasses the useof such additives generally in the amounts indicated above to improvefiberisation of alkaline earth silicate fibres.

TABLE 1 Shrinkage %/24 hrs Composition (wt %) Comp. 1300° c. 1350° c.1400° c. 1450° c. 1500° c. 1550° c. CaO SiO₂ PA Al₂O₃ B₂O₃ ZrO₂ CS01/C10.34 melted melted 35.00 62.40 0.83 CS02/C 8.52 melted melted 33.0063.80 0.77 CS01/D 5.14 32.90 64.60 0.80 CS01 2.60 4.34 melted 33.8065.00 0.80 CS10 4.25 19.51 melted 33.00 65.40 0.76 CS10 cons 4.25 14.12melted 33.00 65.40 0.76 CS02 1.92 2.58 7.83 melted 31.90 66.50 0.77CS02/D 3.85 31.20 66.60 0.75 CMS02 2.12 melted 18.30 66.90 0.31 CMS02/B2.35 7.02 melted 18.30 66.90 0.31 CS03/D 11.87 28.90 69.30 0.70 CMS032.95 melted 16.80 69.40 0.30 CMS03/B 2.75 8.08 melted 16.80 69.40 0.30CS15 5.67 34.47 34.02 28.00 69.70 0.61 CS04/E 2.77 11.39 21.96 28.2069.80 0.61 CS04/E cons 2.77 7.62 28.20 69.80 0.61 CS04 1.65 0.98 3.7130.42 28.20 69.80 0.61 CMS04 2.35 melted 16.50 70.00 0.38 CS12 2.35 9.1031.40 26.90 70.70 0.66 CS12 cons 2.35 4.80 15.37 26.90 70.70 0.66 CS169.37 35.35 34.37 27.20 71.00 0.61 CS17 9.05 33.70 30.64 26.60 71.40 0.62CS18 7.92 32.00 30.02 26.20 71.60 0.75 CS19 4.84 27.36 26.41 26.40 71.600.73 CMS05 2.63 melted 15.10 72.00 0.97 CMS05/B 3.31 8.11 14.10 15.1072.00 0.97 SACM01 4.01 3.56 4.79 3.17 78.00 1.60 SACM02 3.51 5.04 76.501.62 SACM03 5.46 8.63 10.38 7.71 75.80 1.77 CSMg01 7.36 21.14 28.3337.44 23.60 72.90 0.61 CSMg03 2.24 7.17 12.61 20.20 75.70 0.57 CSMg027.14 12.13 16.17 27.03 21.60 75.20 0.54 CSMg07 7.38 20.47 23.00 73.800.49 CSMg06 6.23 25.18 12.34 29.97 24.20 72.30 0.51 CSMg09 1.28 2.3318.30 78.40 0.39 CSMg08 2.86 8.24 9.70 31.43 20.50 76.50 0.44 CSMg101.85 1.80 17.30 79.40 0.28 CS Fe₂O₃ 01 1.94 8.72 19.79 26.24 22.60 74.400.57 CS Fe₂O₃ 05 3.47 10.11 15.34 22.52 21.10 74.70 0.58 CS Fe₂O₃ 021.43 3.64 21.90 74.80 0.56 CS Al 03 2.18 8.47 15.15 22.38 22.30 74.601.03 CS13 1.46 3.00 23.16 24.00 74.30 0.55 CS Fe₂O₃ 04 1.79 9.03 14.5119.78 21.60 74.90 0.52 CS Fe₂O₃ 03 2.43 12.43 20.53 24.24 21.90 74.700.52 CS05 1.21 1.79 4.14 melted 26.40 72.20 0.55 CS06/E 1.56 6.03 21.8130.16 24.00 73.90 0.52 CS06/E cons 1.56 4.02 10.54 13.75 16.96 24.0073.90 0.52 CS Al 02 1.48 2.41 13.51 18.28 23.10 74.70 0.48 CS07/E 1.502.14 10.00 5.19 5.81 22.20 76.50 0.53 CS14/B 2.22 6.23 22.60 75.00 0.58CS08/E 2.03 1.34 3.10 7.72 19.50 78.90 0.70 CS06/B 2.66 melted 12.0024.30 75.00 0.39 Total Composition (wt %) Solubility SSA JM 28 Comp. MgONa₂O K₂O TiO₂ Fe₂O₃ ZnO ppm m²/g Fibre Quality sticking CS01/C 0.56 0.300.15 0.24 230.0 0.33 Coarse Stuck CS02/C 0.51 0.40 0.14 0.22 199.0 0.45Coarse Stuck CS01/D 0.48 0.26 0.15 0.18 199.1 0.37 Coarse Stuck CS010.51 0.21 0.21 235.0 0.47 Coarse Stuck CS10 0.52 0.24 0.15 0.21 199.80.30 Coarse Stuck CS10 cons 0.52 0.24 0.15 0.21 199.8 0.30 Coarse StuckCS02 0.49 0.31 0.20 218.0 0.59 Coarse Stuck CS02/D 0.46 0.25 0.14 0.20208.1 0.42 Coarse Stuck CMS02 14.40 0.17 0.14 213.2 0.42 Coarse StuckCMS02/B 14.40 0.17 0.14 Coarse Stuck CS03/D 0.44 0.19 215.0 0.54 CoarseStuck CMS03 13.40 0.11 0.14 280.1 Coarse Stuck CMS03/B 13.40 0.11 0.14Coarse Stuck CS15 0.53 0.19 0.20 241.9 0.41 Good fibre Stuck CS04/E 0.380.43 0.10 0.17 260.0 0.50 Lots of flake Stuck CS04/E cons 0.38 0.43 0.100.17 260.0 0.50 Lots of flake Stuck CS04 0.38 0.43 0.10 0.17 269.8 0.44Lots of flake Stuck CMS04 13.10 0.12 0.13 Coarse Stuck CS12 0.41 0.390.12 0.18 211.3 0.55 Good fibre Stuck CS12 cons 0.41 0.39 0.12 0.18211.3 0.55 Good fibre Stuck CS16 0.49 0.16 0.17 283.1 0.55 Good fibreStuck CS17 0.48 0.17 0.17 228.2 0.71 Good fibre Stuck CS18 0.49 0.200.18 248.8 0.71 Good fibre Stuck CS19 0.48 0.21 0.19 248.2 0.63 Goodfibre Stuck CMS05 11.40 0.23 0.12 125.2 Coarse Stuck CMS05/B 11.40 0.230.12 Coarse Stuck SACM01 17.00 0.21 160.0 0.37 O.K fibre Not StuckSACM02 14.80 0.12 0.20 206.3 0.33 O.K fibre Not Stuck SACM03 13.10 0.65170.5 0.46 O.K fibre Not Stuck CSMg01 2.61 0.11 0.16 223.6 0.66 Goodfibre some shot Stuck CSMg03 2.61 0.20 0.18 231.3 0.38 Good fibre someshot Not Stuck CSMg02 2.59 0.14 210.6 0.63 Good fibre some shot StuckCSMg07 1.81 0.17 250.1 0.42 O.k fibre Not Stuck CSMg06 1.79 0.13 0.18268.1 0.53 Good fibre Not Stuck CSMg09 1.71 0.14 228.7 0.35 Shotty NotStuck CSMg08 1.65 0.16 257.2 0.43 Good fibre Not Stuck CSMg10 1.61 0.15248.3 0.22 Coarse shotty Not Stuck CS Fe₂O₃ 01 0.72 0.23 0.44 279.9 0.49O.k fibre Not Stuck CS Fe₂O₃ 05 0.51 0.17 2.25 207.1 0.47 Shotty NotStuck CS Fe₂O₃ 02 0.50 0.22 0.65 285.5 0.30 Shotty Not Stuck CS Al 030.41 0.18 0.15 0.48 Good fibre Not Stuck CS13 0.39 0.17 0.17 156.0 0.56Shotty Not Stuck CS Fe₂O₃ 04 0.39 0.16 1.47 239.7 0.41 Good fibre NotStuck CS Fe₂O₃ 03 0.38 0.21 1.06 241.0 0.47 Good fibre Not Stuck CS050.33 0.19 0.10 0.16 262.0 0.45 Lots of flake Not Stuck CS06/E 0.33 0.280.15 222.0 0.34 Lots of flake Not Stuck CS06/E cons 0.33 0.28 0.15 222.00.34 Lots of flake Not Stuck CS Al 02 0.33 0.19 0.14 0.59 Good fibre NotStuck CS07/E 0.33 0.11 0.15 177.9 0.29 O.K fibre Not stuck CS14/B 0.300.12 0.17 137.3 0.55 Shotty Not Stuck CS08/E 0.27 0.16 0.18 160.0 0.32Coarse Not Stuck CS06/B 0.26 0.15 0.12 172.0 0.55 Lots of flake NotStuck

TABLE 2 Shrinkage %/24 hrs Composition (wt %) Comp. 1300° c. 1350° c.1400° c. 1450° c. 1500° c. 1550° c. CaO SiO₂ P₂O₅ Al₂O₃ B₂O₃ ZrO₂ MgOCAS01 17.62 18.45 24.50 71.70 2.78 0.45 0.28 CAS02 10.19 24.18 22.6073.50 2.52 0.91 0.25 CAS03 5.42 14.63 14.56 20.40 75.70 2.32 1.05 0.23CS03/C 6.02 melted melted 31.50 65.60 0.83 0.14 0.47 CZrS02 15.01 31.0827.40 65.80 0.70 3.85 0.40 CZrs03 7.39 30.64 25.60 68.00 0.67 3.96 0.37CS11 4.96 19.95 34.81 29.00 68.90 0.75 0.13 0.47 CS11 cons 4.96 11.4222.67 29.00 68.90 0.75 0.13 0.47 CZrS07 −0.29 17.90 74.70 0.62 4.94 0.24CZrS06 melted 7.97 19.00 74.90 0.71 4.45 0.28 CZrS04 2.56 24.50 70.600.72 3.29 0.36 CS13 cons 1.46 3.56 12.88 16.60 28.58 24.30 73.30 0.570.73 0.31 CAS07 4.59 10.22 24.80 73.10 1.10 0.43 0.28 CSMg04 1.76 2.9416.70 79.40 0.38 0.43 2.35 CS08 1.24 1.30 1.74 3.37 19.80 78.50 0.450.34 0.25 CS05/B 0.86 1.53 5.56 26.00 72.00 0.62 0.33 0.31 CS05/B cons1.53 4.52 13.46 26.00 72.00 0.62 0.33 0.31 CS05/E 2.04 7.28 33.19 44.4926.00 72.00 0.62 0.33 0.31 CS05/E cons 2.04 8.19 20.34 25.44 28.00 26.0072.00 0.62 0.33 0.31 CS06 1.36 1.42 2.36 5.87 melted 23.40 73.30 1.770.27 0.32 CSMg05 1.67 1.26 16.40 79.80 0.35 0.14 2.46 CS07/B 0.86 1.502.17 10.00 15.00 22.20 76.60 0.52 0.12 0.26 CS07/B cons 1.50 1.31 2.935.19 5.81 22.20 76.60 0.52 0.12 0.26 CS07 1.08 1.06 1.15 3.34 22.3076.90 0.35 0.10 0.24 Total Total Composition (wt %) Solubility SSA JM 28SiO₂ + Comp. Na₂O K₂O TiO₂ Fe₂O₃ ZnO ppm m²/g Fibre Quality stickingZrO₂ CAS01 0.12 0.12 30.3 Coarse Stuck 72.15 CAS02 0.11 0.15 20.1 CoarseStuck 74.41 CAS03 0.11 0.12 47.4 0.20 Coarse Stuck 76.75 CS03/C 0.360.14 0.23 222.0 0.31 Coarse Stuck 65.74 CZrS02 0.37 0.12 0.19 107.2 0.39Good fibre Stuck 69.65 CZrs03 0.25 0.11 0.21 64.2 0.21 Good fibre Stuck71.96 CS11 0.30 0.13 0.19 200.5 0.50 Coarse Stuck 69.03 CS11 cons 0.300.13 0.19 200.5 0.50 Coarse Stuck 69.03 CZrS07 0.48 0.17 24.3 0.22 Veryshorty Not Stuck 79.64 CZrS06 0.42 0.13 42.5 0.25 Coarse Not Stuck 79.35CZrS04 0.35 0.11 0.17 69.4 0.21 Good fibre Not Stuck 73.89 CS13 cons0.26 0.20 156.0 0.56 Shotty Not Stuck 74.03 CAS07 0.14 0.14 127.8 0.34Coarse Not Stuck 73.53 CSMg04 0.18 243.0 0.09 Coarse shorty Not Stuck79.83 CS08 0.16 0.14 201.5 0.20 Lots of flake Not stuck 78.84 CS05/B0.22 0.15 182.0 0.34 Lots of flake Not Stuck 72.33 CS05/B cons 0.22 0.15182.0 0.34 Lots of flake Not Stuck 72.33 CS05/E 0.22 0.15 276.0 0.48Lots of flake Not Stuck 72.33 CS05/E cons 0.22 0.15 276.0 0.48 Lots offlake Not Stuck 72.33 CS06 0.14 0.14 244.6 0.32 Lots of flake Not Stuck73.57 CSMg05 0.13 237.2 0.11 Good fibre some shot Not Stuck 79.94 CS07/B0.11 0.12 104.0 0.23 Lots of flake Not Stuck 76.72 CS07/B cons 0.11 0.12104.0 0.23 Lots of flake Not Stuck 76.72 CS07 0.17 0.11 203.5 0.25 Lotsof flake Not Stuck 77.00

TABLE 3 Shrinkage %/24 hrs Composition (wt %) Comp. 1300° c. 1350° c.1400° c. 1450° c. 1500° c. 1550° CaO SiO₂ P₂O₅ Al₂O₃ B₂O₃ ZrO₂ MgO CBS043.54 6.97 7.16 18.00 77.90 0.43 2.03 0.70 0.31 CBS03 3.47 10.32 16.4320.40 75.20 0.48 2.12 0.84 0.33 CPS02/B 4.02 21.40 75.00 1.54 0.48 0.32CPS02 0.66 0.91 0.70 22.40 74.60 1.61 0.29 0.26 0.90 0.27 CPS02 cons0.66 0.25 −0.21 22.40 74.60 1.61 0.29 0.26 0.90 0.27 CPS21 3.04 23.0074.10 0.42 0.61 0.45 CBS05 4.14 9.98 14.71 21.20 73.90 0.54 3.11 0.32CPS20 2.48 9.10 23.80 73.80 0.38 0.66 0.29 0.35 CPS20cons 2.48 6.2111.94 17.39 20.69 23.80 73.80 0.38 0.66 0.29 0.35 CPS18/B 1.93 6.7216.07 23.90 73.20 0.87 0.59 0.34 CPS17/B 2.39 6.36 24.70 72.80 0.88 0.650.36 CPS01/B 1.73 8.96 12.58 23.50 72.70 1.58 0.58 0.33 CPS01/C 2.0511.86 5.87 6.10 23.80 72.60 1.58 0.46 0.34 CBS02 4.93 18.32 23.28 22.9072.60 0.70 2.16 0.30 0.33 CBS07 −0.29 6.10 14.69 24.30 72.20 0.38 1.380.84 0.27 CPS01 2.29 1.25 0.15 23.90 71.50 1.52 0.48 0.90 0.95 0.29CPS01 2.29 1.25 0.15 23.90 71.50 1.52 0.48 0.90 0.95 0.29 cons CPS172.86 25.20 71.50 0.90 0.66 0.37 CPS19 2.87 19.23 26.90 25.50 71.50 0.480.64 0.15 0.39 CBS01 3.79 21.92 25.20 70.90 0.62 2.13 0.84 0.41 CPS15/B2.24 12.71 27.90 35.55 27.00 70.50 0.83 0.64 0.39 CPS16 3.96 20.90 27.9026.00 70.20 0.89 0.69 0.23 0.38 CPS15 2.76 13.37 28.94 26.70 70.00 0.930.69 0.43 CPS15 cons 2.76 14.74 17.67 26.70 70.00 0.93 0.69 0.43 CPS14/B4.08 28.80 29.70 67.70 0.90 0.69 0.46 CS03 1.36 1.55 5.03 melted 30.2067.60 0.15 0.87 0.42 CS03/E 3.81 18.22 melted melted 30.20 67.60 0.150.87 0.42 CS03/E cons 3.81 13.67 28.02 30.20 67.60 0.15 0.87 0.42 CPS136.92 4.00 38.52 30.20 65.70 0.93 0.70 0.47 CPS14 1.90 13.10 melted 30.8064.80 0.99 0.80 0.48 CPS14 cons 1.90 5.30 11.68 15.88 30.80 64.80 0.990.80 0.48 CPS12 8.72 5.93 melted 32.10 63.80 0.89 0.75 0.49 CPS11 15.7210.06 melted 34.40 62.00 0.99 0.81 0.10 0.55 Total SiO₂ + Total B₂O₃ +Composition (wt %) Solubility SSA Fibre JM 28 ZrO₂ + Comp. Na₂O K₂O TiO₂Fe₂O₃ ZnO ppm m²/g Quality sticking 5*P₂O₅ CBS04 0.17 0.24 64.0 0.16Coarse Not stuck 80.63 CBS03 0.18 0.18 73.0 Coarse Not stuck 78.16CPS02/B 0.13 0.16 336.0 0.27 Coarse Not Stuck 82.70 CPS02 0.21 0.11349.6 0.10 O.K fibre Not Stuck 83.81 CPS02 cons 0.21 0.11 336.8 0.10Coarse Not Stuck 83.81 CPS21 0.38 0.10 0.20 188.0 0.41 O.K fibre NotStuck 76.20 CBS05 0.16 0.17 117.0 0.35 Coarse Not Stuck 77.01 CPS20 0.180.11 0.16 229.0 0.33 Good fibre Not Stuck 75.99 CPS20cons 0.18 0.11 0.16229.0 0.33 Good fibre Not Stuck 75.99 CPS18/B 0.19 0.15 161.0 0.42Shorty Not Stuck 77.55 CPS17/B 0.17 0.16 152.0 0.58 O.K fibre Not Stuck77.20 CPS01/B 0.20 0.15 275.0 0.34 Good fibre Not Stuck 80.60 CPS01/C0.32 0.32 338.8 0.50 Coarse Not Stuck 80.50 CBS02 0.24 0.15 85.0 Goodfibre Not stuck 75.06 CBS07 0.18 0.13 90.0 0.32 Snotty Not Stuck 74.42CPS01 0.48 0.10 286.3 0.13 O.K fibre Not Stuck 80.95 CPS01 0.48 0.10338.8 0.13 Coarse Not Stuck 80.95 cons CPS17 0.37 0.11 0.28 241.0 0.49Shotty Not Stuck 76.00 CPS19 0.44 0.11 0.18 172.0 0.40 Good fibre NotStuck 74.05 CBS01 0.12 0.20 101.2 0.45 Good fibre Not Stuck 73.87CPS15/B 0.15 0.17 177.0 0.38 Coarse Stuck 74.65 CPS16 0.53 0.11 0.18181.0 0.54 Coarse Not Stuck 74.88 CPS15 0.38 0.12 0.20 166.6 0.61 CoarseNot Stuck 74.65 CPS15 cons 0.38 0.12 0.20 166.6 0.61 Coarse Not Stuck74.65 CPS14/B 0.19 0.10 0.22 153.9 0.32 O.K fibre Not Stuck 72.20 CS030.21 0.11 0.18 240.5 0.61 Coarse Stuck 68.35 CS03/E 0.21 0.11 0.18 260.00.47 Coarse Stuck 68.35 CS03/E cons 0.21 0.11 0.18 260.0 0.47 CoarseStuck 68.35 CPS13 0.54 0.13 0.20 163.8 0.44 O.K fibre Stuck 70.35 CPS140.30 0.13 0.21 153.9 0.47 O.K fibre Stuck 69.75 CPS14 cons 0.30 0.130.21 153.9 0.47 O.K fibre Stuck 69.75 Lots of CPS12 0.31 0.14 0.20 165.60.55 flake Stuck 68.25 CPS11 0.31 0.13 0.21 170.5 0.53 Good fibre Stuck67.05

TABLE 4 Shrinkage %/24 hrs Composition (wt %) Comp. 1300° c. 1350° c.1400° c. 1450° c. 1500° c. 1550° c. CaO SiO₂ P₂O₅ Al₂O B₂O₃ ZrO₂ MgO 50%YIELD 0.64 1.30 6.78 28.55 30.83 25.50 72.70 0.59 0.50 SPUN 0.38 0.775.48 30.54 40.30 25.40 73.10 0.67 0.54 BLOWN 0.80 1.30 7.89 29.43 39.6425.30 73.10 0.54 0.55 Blanket 0.61 0.90 23.00 74.60 0.56 0.43 BAG 240.85 1.43 4.69 18.36 25.69 23.18 75.18 0.66 0.42 BAG 7 0.57 0.84 2.2222.32 26.70 24.26 73.95 0.63 0.45 BAG 41 0.83 1.02 1.51 12.12 17.8521.62 76.65 0.79 0.38 BAG 46 1.56 0.96 1.36 7.69 12.84 18.70 79.80 0.810.43 BAG 62 0.65 3.24 8.33 13.25 22.84 19.74 76.25 0.47 0.82 2.27 No. 33.36 8.02 19.94 75.35 0.37 1.11 2.99 No. 4 2.54 8.12 20.81 75.45 0.391.05 2.87 No. 5 1.96 6.55 20.61 75.28 0.36 0.99 2.70 Blanket 1st 0.5423.80 74.20 0.62 0.77 Blanket Last 1.13 1.37 6.00 16.21 28.76 melted25.01 72.89 0.57 0.92 Blanket 1st 1.28 1.79 2.56 27.17 25.11 23.80 74.200.62 0.77 Blanket Last 1.06 1.35 1.71 21.38 31.51 25.01 72.89 0.57 0.92Bulk Hi Speed 1.52 1.81 13.71 24.15 24.56 24.90 72.20 0.72 0.82 TotalComposition (wt %) Solubility SSA Fibre JM 28 Comp. Na₂ K₂O TiO₂ Fe₂O₃ZnO ppm m²/g Quality sticking 50% YIELD 0.26 0.19 232.0 0.22 Very goodNot Stuck SPUN 0.18 254.0 0.23 Very good Not Stuck BLOWN 0.22 196.8 0.47Very good Not Stuck Blanket 0.22 0.12 0.17 240.7 0.16 Very good NotStuck BAG 24 0.17 300.0 0.23 Very good Not Stuck BAG 7 0.19 117.0 0.16Very good Not Stuck BAG 41 0.17 127.0 0.17 Very good Not Stuck BAG 460.14 62.0 0.17 Very good Not Stuck BAG 62 0.15 95.0 0.16 Very good NotStuck No. 3 0.16 202.8 1.15 Very good Not Stuck No. 4 0.16 210.2 0.61Very good Not Stuck No. 5 0.16 229.4 0.88 Very good Not Stuck Blanket1st 205.2 0.41 Very good Not Stuck Blanket Last 264.4 0.15 Very good NotStuck Blanket 1st 205.2 0.41 Very good Not Stuck Blanket Last 264.4 0.15Very good Not Stuck Bulk Hi Speed 267.5 0.15 Very good Not Stuck

1. Thermal insulation comprising fibres having a composition in wt %72%<SiO₂<86%0<MgO<10%14%<CaO<28%Al₂O₃<2%ZrO₂<3%B₂O₃<5%P₂O₅<5%95%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 2. Thermal insulation as claimedin claim 1, in which the amount of MgO present in the fibre is less than2.5%.
 3. Thermal insulation as claimed in claim 2, in which the amountof MgO present in the fibre is less than 1.75%.
 4. Thermal insulation asclaimed in claim 1, in which the amount of CaO is in the range18%<CaO<26%.
 5. Thermal insulation as claimed in claim 4, in which theamount of MgO present in the fibre is less than 1.75%.
 6. Thermalinsulation as claimed in claim 5, in which98%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 7. Thermal insulation as claimedin claim 6, in which98.5%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 8. Thermal insulation asclaimed claim 7, in which99%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 9. Thermal insulation as claimedin claim 1, in which98%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 10. Thermal insulation as claimedin claim 9, in which98.5%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 11. Thermal insulation asclaimed claim 10, in which99%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 12. Thermal insulation as claimedin claim 1, having the composition:—72%<SiO₂<80%18%<CaO<26%0%<MgO<3%0%<Al₂O₃<1%0%<ZrO₂<1.5%98.5%<SiO₂+CaO+MgO+Al₂O₃+ZrO₂+B₂O₃+P₂O₅.
 13. Thermal insulation asclaimed in claim 1, in which:—72%<SiO₂<74%24%<CaO<26%
 14. Thermal insulation wholly comprising fibres as specifiedin claim
 1. 15. Thermal insulation as claimed in claim 1, in which thethermal insulation is in the form of a blanket.
 16. Thermal insulationas claimed in claim 5, in which the thermal insulation is in the form ofa blanket.
 17. Thermal insulation as claimed in claim 14, in which thethermal insulation is in the form of a blanket.